Will Windows 8 on ARM include support for the traditional Windows desktop? …

Ever since Microsoft first announced that Windows 8 would be compatible with certain ARM system-on-chip processors, questions about what this would mean for existing Windows applications have been abundant. ARM's strength is in low-power applications, and the decision to support the architecture was plainly motivated by the needs of the tablet market—which left observers wondering just how much of Windows would actually be supported on ARM? Just the bits relevant to tablet and consumer applications, or the whole shebang?

When Microsoft revealed and then described Windows 8's Metro-style tablet interface, the company left the ARM questions unresolved. Windows 8 has two distinct kinds of application: traditional Windows applications that run on the desktop, and new finger-friendly Metro-style applications, with the latter integrated into the new Start screen, and the former segregated off into a separate desktop. This led to speculation that ARM Windows might support only Metro-style programs, and exclude the desktop altogether.

Microsoft still isn't saying one way or the other, but long-time Microsoft-watcher Paul Thurrott claimed on Thursday that sources he trusted had told him that ARM Windows would be Metro-only: the Windows desktop, and the ability to run legacy Windows software, would be omitted. The following day, Thurrott reported that other sources he trusted disagreed, and that ARM Windows would support the desktop after all.

While this leaves us no closer to knowing the truth, we think that both answers could—and should—be correct. It makes sense to produce at least one Windows SKU that has no legacy desktop, but equally, it makes sense to produce at least one SKU that runs on ARM and does include the legacy desktop.

The case for not having a legacy desktop is simple enough. The tablet market is the one most seriously constrained by x86's relative power hunger, and the tablet market is the one in which the legacy desktop is least useful. While Metro-style applications will be finger-friendly and suitable to tablet usage, legacy applications tend to demand the mouse and keyboard—the very problem that has rendered Windows unsuitable for tablet computers for more than a decade.

As such, ARM makes the most sense in tablets, and the ability to run legacy applications has the least value in tablets.

Moreover, as we've argued before, having a version of Windows 8 without the desktop at all keeps Microsoft honest: it means that the company can never fall back on, say, "use the traditional Control Panel to configure these options," because there won't be a traditional Control Panel to use.

Of course, there's no reason why this version should be restricted to ARM. Should iPad-like x86 tablets be invented and marketed, it might just as well run a no-desktop version of Windows too.

The argument in favor of retaining the legacy desktop, even on ARM, is more nuanced. One of the few things that Microsoft has been clear about is that Windows 8 on ARM won't include any kind of x86 emulator. Current x86 programs simply won't run on any version of Windows 8 on ARM. On the face of it, this would limit the desirability of the legacy desktop—with no legacy applications, who needs a backwards-compatible, legacy desktop?

Although tablets are the obvious target for ARM processors, they needn't be the only one. ARM's power efficiency isn't just relevant to tablets; it might be valuable in laptops, too. While legacy x86 applications won't run on ARM, business applications written using .NET should run unmodified, and—as long as ARM Windows really is Windows, and contains all the things that regular Windows contains—recompiling existing applications to run on ARM should be a relatively trivial affair.

Applications already ported to support 64-bit processors, a category that includes Microsoft's own Office, will be in a particularly strong position, as their code should already have been purged of any processor-dependent portions.

A low-power, long-battery-life ARM laptop, capable of running Metro-style applications and other modern, recompiled software, would be a viable proposition for many users.

Corporations concerned about power and HVAC costs might even want to roll out slimline, low-power ARM desktops to office workers. In these situations, even the occasional x86-only application might not be a deal-breaker, as such it might be possible to run such applications remotely, using virtualization.

Looking beyond the desktop, ultra-high density ARM servers are coming to market, and while these machines won't run Windows, if ARM gains traction in this kind of market, it's inevitable that demand for Windows ARM Servers will materialize. While server applications typically don't need the "desktop" as such, they do tend to need many of Windows' other platform features—platform features that a non-desktop version could exclude.

While good arguments can be made to offer ARM versions of Windows 8 both with and without a desktop, the no-desktop version does pose a particular problem for Microsoft. The company has long insisted that tablets are just a kind of PC, and the thing about PCs is that they run PC programs. Without a traditional desktop, PC programs are off-limits.

If Microsoft plays up the PC-ness of Windows 8 tablets, and markets them as "more" than competing tablets, a version without a desktop becomes a positive liability.

I don't they'll remove the desktop, because Microsoft did a huge effort in trying to have all the ARM API code match the one for x86. They even said, that all a manufacture needs to do pretty much, is recompile their software for ARM, and they are done (in DevBuild keynote).

I don't think the logic that desktop app not being usable on desktop is valid. If the application is made for ARM system (which is tablets), then OBVIOUSLY the GUI will be changed to have big buttons and stuff for easy finger manipulation, resolving the problem.

The Windows directory on the corp Win7 machine here is 13.0GB. It needs to shrunken and trimmed... A LOT... to be viable on the typical 16-32GB ARM tablets.

I'm not sure how much space is saved by leaving out the classic desktop and GUI, but it would be a start.

Actually legacy desktop is pretty large or atleast we can estimate it. Look at Server 2008 R2 core vs R2 standard. Core's base install is almost half that of standard, and really the only change for the most part is the entire UI is gone.

The Windows directory on the corp Win7 machine here is 13.0GB. It needs to shrunken and trimmed... A LOT... to be viable on the typical 16-32GB ARM tablets.

It has been. Look at Ars's article on the revamped Win8 Installer.

To me, the ideal balance would be:

1. ARM tablets only have the new interface, as they don't need to support legacy anyway.2. x86 tablets support both, for users like me that want to run legacy code on a tablet, and understand the battery trade-offs (bit of an edge case)3. Traditional desktop users, which will primarily still run the desktop version.

It would make sense to limit the ARM experience to metro because at least that would avoid confusion and fragmentation. "It's windows but it can't run anything" isn't going to go over that well. It's far easier to support and market a limited metro only device than a completely alternate incompatible platform.

This whole ARM experiment is a waste in my mind because soon enough intel will have low enough power chips to fit into tablets anyways. Microsoft would have been better off saving the resources expended on ARM and putting them towards making windows that much better on X86.

EDIT: Apple came in and told everybody what a tablet is; a limited device very distinct from the PC. Microsoft, having missed that boat has the unique opportunity to leapfrog Apple and show everybody what the tablet is going to be. The way to do this would be to wait until technology has sufficiently blurred the line between the tablet and the PC and come in with a carefully tailored platform that bridges both. This would be a move that Apple itself, with it's very distinct platforms, is inevitably going to have a tough time doing.

You could argue that this is exactly what windows 8 is but I'm not convinced. Microsoft has never executed a move this bold and I tend to think it can only be done right if it's a clear goal: "Define the next gen tablet". Instead I think Microsoft is thinking "Crap, lets get a tablet out quick" and they are using windows to do that. The ARM thing further shows they lack focus and are grasping at things to get out there quick. Windows 8 looks somewhat intriguing so far so perhaps they are stumbling in the right direction. But I'll wait and see.

Considering that, what good would the Desktop be? We need to consider realistic situations. The "real" Win 8 tablet is x86. Not only that, but the example we saw was running a mobile i5 CPU. This was large, 11.6" or so, heavy, hot, and likely expensive.

ARM devices will probably be 10", light, cool, and less expensive. We all know that even the most powerful Atom chip is a sad reflection of even the i3, and yet Samsung used an i5 for the demo model. No doubt with Ivy Bridge being out by the time this comes out, it will be better all round. But, no matter how good ARM is getting, it's still less powerful than the somewhat despised Atom, which runs win 7 poorly.

I can't see programs that are designed for the much more powerful x86 line running on an ARM, even though re-compiled. The power simply isn't there, and won't be for years.

In addition, there will still be all of the problems using a stylus on Win7 type apps, more so that with the larger, higher Rez x86 tablets, which are larger precisely for that reason.

So, what is the point of having that Desktop in a Metro tablet on ARM? I can't think of a single one as being practical.

From a marketing perspective, the answer is obvious, tablets shouldnt expect to run any desktop apps, you'll need to buy new ones in the store. Traditional x86 laptops will be able to run everything. In fact, I can probably see Mucrosoft preventing the release of ARM-based notebooks for a while so users aren't confused why their old software doesn't work in Windows 8.

But leaving out desktop apps is for the better. Higher demand for Metro apps means more developers on the platform and a better experience for all. And for those businesses that need to run their .NET applications, x86 tablets are sure to exist. But if they want great battery life too, they'll either have to wait on Intel or rewrite their apps to be mobile friendly. Besides, without a UI redesign to be touch-friendly, you've basically resurrected the 2002 tablet, and we all know how well those sold.

Microsoft needs to put its foot down a d prioritize user experience and battery life first over backwards compatibility. Build a create platform and the apps will come, as evidenced by the fact that the iPad has over 150,000 tablet specific apps in less than 2 years.

The Windows directory on the corp Win7 machine here is 13.0GB. It needs to shrunken and trimmed... A LOT... to be viable on the typical 16-32GB ARM tablets.

I'm not sure how much space is saved by leaving out the classic desktop and GUI, but it would be a start.

Between the device driver catalog and the side-by-side assemblies, you are looking at near half the 13GiB used. There are a lot of places that can be cut for tablet installation, and getting rid of the legacy desktop helps in a big way.

I wouldn't run any desktop apps on my tablet anymore than I would run Metro on my computer desktop. I maybe wrong, but I doubt people will be doing much major software development, desktop publishing, or Excel macro writing on an ARM. However, it's probably a good bet people on computer desktops are doing all the above, in addition to gaming.

So bottom line, why force the desktop on an ARM tablet as it will be as well useful as booting up in Metro on dual 20 inch monitors running on a desktop with the latest core i7 architecture and 16 gig of RAM.

Tangentially related to this: I'm thinking MS's long term goal is to unify Windows Phone and Windows "Desktop". Maybe Windows 9 will be running on phones? Seems like Apple is heading down this route as well (combining desktop and phone/tablet OS's).

The Windows directory on the corp Win7 machine here is 13.0GB. It needs to shrunken and trimmed... A LOT... to be viable on the typical 16-32GB ARM tablets.

It's actually physically a hell of a lot smaller than that - Windows uses symlinks in WinSxS to keep track of update and services information so that counts files several hundred times (mine "takes up" 150GB), you won't get an accurate reading of Windows disk space by doing a DIR /S.

IIRC it's about 2-3GB, which isn't bad.

Personally I think they should sell a Metro-only ARM Windows 8, it'd be easier for everyone and give ARM tablet users the best experience, if you want desktop buy an x86 tablet or laptop. By 2012 x86 tablets will be approaching today's ARM tablets for power consumption anyway, so the biggest advantage ARM tablets will have is price and even superer-duperrer battery life.

One thing to consider is that, so far, Microsoft has said that it plans to limit the distribution of Metro-style applications to the Windows App Store. So that means that no legacy desktop = no side-loaded apps without a jailbreak.

Personally, I would like to see the desktop included in tablets. I think it should at least be available when the user docs the tablet into a keyboard and mouse. That way they could have metro-style apps while on the move, but traditional full-featured mouse/keyboard apps at home, meaning that the tablet would be the only computer many people need.

"recompiling existing applications to run on ARM should be a relatively trivial affair."

If I've learned anything as a code auditor, it's that there's no such thing as a trivial recompile

Hopefully they'll be using .NET so it's pretty easy... just need to QA/test.

I'm curious as to why seemingly everyone has assumed Microsoft will port the .NET framework to ARM. I haven't seen any indication that they have. WinRT is separate from .NET even though you can compile .NET's languages to it. It's certainly possible; the .NET Compact Framework already runs on ARM (smartphones), but the CF is a small part of the complete framework. Porting the full framework could mean a lot of resources that would be better put toward other, more important endeavors.

One thing to consider is that, so far, Microsoft has said that it plans to limit the distribution of Metro-style applications to the Windows App Store. So that means that no legacy desktop = no side-loaded apps without a jailbreak.

Considering MS is now allowing side-loading of apps to Windows Phone now, I imagine it won't require a jailbreak, just a conscious effort on the part of the user to turn on the ability to allow it.

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I'm curious as to why seemingly everyone has assumed Microsoft will port the .NET framework to ARM.

What problem is desktop apps on tablets solving? Who is the market for this? Business surely, and I can imagine MS doing very well in that very important segment with this implementation. But in the consumer space who gives a shit?

Desktop apps on tablets feels like "your mom will love the Tegra 2 processor" writ large; consumers don't care. If its too complicated they won't bother. This sounds complicated to sell, so the manufacturers are fighting an uphill battle from the start.

I'm trying to figure out what competitive advantage, if any, an ARM metro-only Windows 8 tablet would have. Developers universally would have rewrite their applications, so the traditional Microsoft platform lock-in no longer works. Office would have be overhauled to work in a tablet form factor so it wouldn't really be the same old Office (although I've seen theories that the ribbonification of MS apps is part of making it more touch-friendly). Existing Win32 code presumably could be ported, although it's unclear how big of an advantage this would have compared to porting to Android or iOS since the code most likely to be deeply entwined with Win32 would be GUI related. Finally, as other people have said, this creates a bit of a marketing problem trying to explain that Windows is a kernel, not a desktop. It seems like MS has a platform fragmentation problem; between XBox, WP7 and Windows you can use the same *technologies* to develop apps, but actually writing *cross-platform* apps is much harder.

Keep the desktop out of the customer versions of ARM Tablets. Exactly to your point that it keeps MS honest and it avoids confusion with people trying to install their 10 year old version of Hearts and other old software.

But I think there is a market for power users. Lenovo might want to make a ThinkTab for IT professionals that need to run special software that is compiled for the ARM version of Win32. They could get this through a special SKU or, even better, make it available as a download like WinXP mode in Win 7.

This way it avoids confusion with the consumer and makes it available for the professional.

I don't get why the desktop is being referred to as legacy. MS did make some changes and add new features to the desktop, create a verison of the desktop for ARM and go through the trouble of implementing two UIs to accomdate the desktop, are all things not done for a legacy product.

Metro could flop, and isn't safe to assume that it will be a runaway success.

Honestly I don't see the point since allowing a ARM based verison of the desktop. It just invites malware on the tablets, driver issues and etc. Even if some decide to compile an ARM verison of a program since it existed outside of MS walled city, distributing it would be a challange. Metro and Metro apps is clearly the focus of the ARM verison and of tablets and that is where Metro performs the best.

If people wanted to use Windows in a tablet form factor then existing Windows Tablets would have been alot more successful.

The ultimate tablet, and the one I'm still waiting for, is a 12" ARM tablet with a digitizer, and a separate keyboard attachment that contains a battery, like the Asus Transformer. That would give you the 16 hour battery life in addition to the ability to take detailed notes with a stylus, and you would still be able to use the standalone tablet around your house or wherever if you wanted to.

I don't know why companies are so afraid of trying something different.

Considering MS is now allowing side-loading of apps to Windows Phone now, I imagine it won't require a jailbreak, just a conscious effort on the part of the user to turn on the ability to allow it.

I hope you're right. I'm just going by what they said in the Build event videos, which was something like "Metro Style apps will be distributed only through the Windows app store, with some mechanism for developers and large corporations to bypass it."

They certainly made it sound like it's going to be required, and didn't mention any way for regular users to bypass it. I'm worried it's going to end up working like the limited way that developers can sign an application that can only run on their own iOS device and the devices of a limited number of beta testers. Their rationale seems to be that developers who want to release applications without paying for membership or going through the certification process can still release desktop apps.

Of course I realize this is all subject to change when it's actually released, and I hope that you're right that it will be easy to bypass.

"recompiling existing applications to run on ARM should be a relatively trivial affair."

If I've learned anything as a code auditor, it's that there's no such thing as a trivial recompile

Hopefully they'll be using .NET so it's pretty easy... just need to QA/test.

It won't be easy. It will be very hard.

It's not even the question of going from Win 7 to Metro, it's going from x86 to ARM. These are very different chip families. There is no guarantee that what works on one will work on the other. Programming models are pretty much different. NET is only part of it. The x86 family is much more powerful than the ARM family. Remember Gates's statement many years ago that MS's job was to add features, and the job of the chip and computer manufacturers was to make computers fast enough to run it properly. Well, ARM isn't fast enough to run it properly. There will need to be major changes, and likely the dropping of features that require too much RAM and power.

Whatever comes of those apps will be very different than the present versions. So different, that they will be different apps entirely, though they may share the basic name.

Let's face it, METRO on ARM is a different device family, and a different OS family. Even apps written for Metro on x86 will need to be different.MS can't make the mistake of leading people on to believe that this is "Windows Everywhere" as they love doing. If people take these things home, and find they can't run their regular Windows programs, which they will find, then a lot of them will be coming back, if Ms hasn't painstakingly explained this all first.

Remember the first netbooks. People bought them, and then they returned them. Why? Because they didn't understand that they ran Linux, and that Linux didn't run Windows apps.

Of course, there's no reason why this version should be restricted to ARM. Should iPad-like x86 tablets be invented and marketed, it might just as well run a no-desktop version of Windows too.

You mean like The Samsung Series 7 Slate? Running a core i5 with Windows 7 right now, but the Windows 8 preview loads on nicely and runs great.

As someone who has used a windows Vista and then windows 7 tablet for the last 4 years, I can't imagine going back to a portable machine that DOESN'T have touch on it...laptop, tablet, OR slate format. Pen input is a big bonus, too. The only thing I wish it had that it doesn't right now is higher resolution screen...but that won't take forever to happen.

The most likely scenario is that you are going to get both, a "Tablet Edition" that is very low priced and only supports Metro apps and all other editions will also run on Tablets (since they are just another PC configuration) as well as Ultrabooks, Desktops, etc. and supports Desktop Apps. This will also be on ARM, even though that requires software authors to (at least) recompile their code. I explore this more fully on my blog: http://hal2020.com/2011/12/04/will-wind ... ktop-apps/

No, it's pretty clear that it won't run x86 applications. Beyond that, nobody knows, and any journalist speaking authoritatively about the matter is a liar.

I'm not sure if you're disagreeing with me or not. If so, then be advised that x86 and Win 7 programs, not apps, are one and the same.

And I would think that confirmation by Sinofsky should be authoritative enough. The question is what purpose would the Desktop serve if not to run "Desktop programs" I can't see MS requiring people to use a stylus on some kind of bastardized version of a Win program on a 10" screen. It will be hard enough on an 11.6" screen.

And if they all go though, then why have the Desktop at all? Why go through all that complexity?

"recompiling existing applications to run on ARM should be a relatively trivial affair."

If I've learned anything as a code auditor, it's that there's no such thing as a trivial recompile

Hopefully they'll be using .NET so it's pretty easy... just need to QA/test.

It won't be easy. It will be very hard.

It's not even the question of going from Win 7 to Metro, it's going from x86 to ARM. These are very different chip families. There is no guarantee that what works on one will work on the other. Programming models are pretty much different.

Or pretty much identical, as Mac OS X developers making the leap to iOS have discovered.

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NET is only part of it. The x86 family is much more powerful than the ARM family. Remember Gates's statement many years ago that MS's job was to add features, and the job of the chip and computer manufacturers was to make computers fast enough to run it properly.

Gates doesn't run Microsoft any more, and hasn't for many years. Windows Vista, Windows 7, and Windows 8 will all have the same system requirements. The demands of the operating system simply haven't grown to keep up with hardware improvements.

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Well, ARM isn't fast enough to run it properly. There will need to be major changes, and likely the dropping of features that require too much RAM and power.

ARM is fast enough. A typical Cortex A15 laptop will have more per-thread performance than the (admittedly quite slow, 1.2 GHz Core 2 Duo) laptop I'm using now, will have more threads than the laptop I'm using now, and will use less power than the laptop I'm using now. And yet, this laptop is more than adequate for Web browsing and Office.

ARM is slower than x86, certainly. But that's beside the point. A15 parts will be fast enough, and that's all that matters.

No, it's pretty clear that it won't run x86 applications. Beyond that, nobody knows, and any journalist speaking authoritatively about the matter is a liar.

I'm not sure if you're disagreeing with me or not. If so, then be advised that x86 and Win 7 programs, not apps, are one and the same.

If I take a Windows 7 program and flip the compiler switch to produce an ARM or MSIL binary, what do I have? Will it run on ARM Windows 8?

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And I would think that confirmation by Sinofsky should be authoritative enough. The question is what purpose would the Desktop serve if not to run "Desktop programs" I can't see MS requiring people to use a stylus on some kind of bastardized version of a Win program on a 10" screen. It will be hard enough on an 11.6" screen.

Sinofsky has confirmed only that ARM systems won't be able to run x86 executables.

What's the point of even keeping around the traditional desktop in the first place? Just to run legacy x86 applications? No, you don't need an entire Windows 7 look-alike desktop to do that. They could have better integrated legacy x86 applications with the new metro ui. The whole *lets have two interfaces* thing just annoys me.